Burner control means



20, 1945. w, s, LANDQN 1 2,389,519

BURNER CONTROL MEANS I Filed Sept. 4, 1942 2 Sheets-Sheet 1 INVENTOR m J. M44

h, ATTORNEY Nov. 20, 1945. w. s. LANDoN 2,389,519

BURNER CONTROL MEANS Filed Sept. 4, 1942 I 2 Sheets-Shet 2 INVENTOR mum, ,4 BY A. M

M ATTORNEY Patented Nov. 20, I

OFFICE I w UNIT-ED STATES PATENT 2,389,519 I BURNER CONTROL MEANS Walter S. Landon, Detroit, Mlclu, assignor to Detroit Lubricator Company, Detroit, Mich a I corporation of Michigan I Application September 4,1942, Serial No. 457,810

11 Claims.

\ This invention relates to new and useful improvements in heating apparatus and more particularly to means for" controlling the operation of a burner for the same.

An object of the invention is to provide conwith combustion air through an-air inlet I, either natural draft or pressure fed by a fan or the like. The combustion chamber ll has an outlet duct 9 trol means for a heating apparatus which is par- 6 to the usual stack orchimney. Surrounding the ticularly adapted for use with so-called floor furcombustion chamber 5, there is a continuous vernaces, in that safety means is provided for stoptical partition or baflie Ill dividing the space withping operation of the apparatus in theevent of in the casing ll of the heating apparatus into excess temperature of the apparatus. 10 a return air inflow passageway l2 for receiving Another object is to provide means for autoair from the heated sp ce and an upflow dismatically regulating the heat output of the heath r p ssa w y ii for the heated vall which mg apparatus; discharges through the grill 3 into the space to Another object is to provide novel means for b h ted. The baflie W terminates above the determining the range of automatic operation base of the heatin pp ratus so that the P and the maximum and minimum flow limits of v 'sageway as is in communication at its lower end the fuel supplyingvaive for the heating appara- .with the lower end of the upflow eway it, tus. I The liquid fuel is fed through the pipe or con- Another object is to utilize the excess oil lever duit i from a cons t liquid level control device safety trip mechanism of a constant liquid level M which is supplied with fuel from a supple tank control means to stonoperation of. the heating I not-shown through inle s pp y pipe iii apparatus upon occurrence of an undesired high which is connected into an inlet-strainer chamber temperature or the heating apparatus, It in the base of the device It; The outlet from Another object is to utilize the automatic heat he Strainer l1 n chamber l3 p ns n a D 8- output regulating means for actuating the safety saseway. It which opens upw u h a V lve trip mechanism. I seat member l9 into the constant level chamber The invention consists in the improved conor reservoir 20 of the device M. Cooperable with struction and combination of parts and their agthe seat member ll there is a float operated inletgrcupment in operative relation to be more fully on oll n nd sh t-0f! nee le valve 2! for r su- 1 described hereinafter and the novelty of which lat n he infl w 01 Oil to the reservoir 20. The will be particularly pointed out and distinctly valve M is secured't a float operated'lever arm claimed. In the accompanying drawings to be .22 fulcrumed iorjnormal operation on a pinwzt taken ass part of this specification. there. is fully and carry n a float memb r 24. a iusta le laand clearly illustrated a prefered embodiment of tive to the arm 22 by means of a screw 28 encasethe invention, in which drawings; able with the bimetal float supporting member I Figure 1 is a schematic view of the heating ap- 28. The arm 22 is provided with hearing slots paratus having the novel control means and 21 cooperable with the pin 23 so that in the event showing the control means in side elevation but of failure of the valve 2| to maintain a constant with parts broken away and in vertical section liquid level such that the liquid level substantially on the line l-i -of Figure 2; the arm 23 can fulcrum on the connecting pin Fig. 2 is a top plan view of the control means 28 between the arm 22 and valve member '2l, with the top'eover member removed; thereby to permit the float member 26 to move Fig. 3 is a view of the control means in vertical I upward due to the lost motion permitted at the central section on the line H of Fig. 2; I slots 21. Upward movement of the float 24 in re- Fig. 4 is a detail view showing certain of the spouse to excess or undesired increase in liquid safety mechanism and taken on the line 4-4 01 I level will cause the lever arm extension 28 to enng, 3; I gage the trip arm 30 of the safety trip mecha- Fig. 5 is a detail exploded view of parts of the nism 8| and move the dog or pawl 32 out of unvalve positioning mechanism; i I derlying relation to the latch plate 28 on the pig. .6 is a detail view in section on the line H 0 safety trip lever 34 so that the force of the spring of Fig. 3 showing the cooperation of the metering 3 is released to move the lever sharply downvalve and m opergting and v ward into engagement with the upper end of the m, 7 1 a d mn view o certain k mppo valve member 2|, thereby to force it to closed 1mm, I position against its seat. The safety trip lever Referring to the drawingsby characters of ref- 34 h an end Portion which extends O ercncc. I designates generally a heating apparah casing 31 of the device l4 so that t p tus such as afloor furnace supported by a basemechanism can be by 1 "W on merit floor orthe like 2 and discharging the the lever end II. The trip arm I. also has an heated air upward through a grill 3 set in the end portion 30 which extends out of the casing floor l. The heating apparatus has a combuse0 31 so that the lever 34 can b ly ipp tion chamber I with a pot-type oil burner I which or released. A more compl e ption of this sel 2,317,556, granted April 27, 1943, for Liquid ing pin 12. The other end of the lever H has a laterally projecting arm 13 which underlies the member 33 having a to'p'cover member 40 and a horizontal supporting member such as a plate cast integral with the housing 33 and extending across one end portion of the housing 38 in overlying relation to thetrip mechanism 3 l Secured to the underside of the supporting member 4! by screws or the like 42, there is a temperature responsive power element 43 having a casing 44 closed and sealed by an expansible, collapsible wall 45, such as a metal bellows to provide an expansion chamber 48 communicating with a bulb or feeler element 41 through a capillary tube 48. The power element is charged under a vacuum with a suitable volatile liquid such as aniline oil. The bulb element 41 is inserted through the heating apparatus casing H into the upflow passageway l3 so that the .pressure in the expansion chamber 48varies in accordance with the temperature of the heated air discharging to the spaceto be heated. The bellows head or end wall 49 has an upward extending thrust member 50 from which a spring abutment post'5l extends concentrically upward. Straddling the post is the bifurcated end portion 52 of an operating lever 53 which is journaled on a bearing pin 54 supported'in oppositely disposed brackets 55 on the top .face of the supporting plate. The post 5| has oppositely positioned downward directed knife edge members 58 which seat in end recess in the bifurcated end portion 5| of a leaf spring member 58 which straddles the post 5|. The spring member 58 extends longitudinally and in overlying relation to the lever 53 and terminates adjacent the opposite end of the housing 33 in an adjustment screw engaging portion 53 cooperable with an adjustment screw 60 bearing downward against the-spring 58 and tensioning it over a bridge member 6| which supports the spring 58 intermediate its ends. The lever 53 has a downturned spring-abutment arm 62. Positioned between the arm 62 and an abutment member 63 secured to the housing 33, there is a rebent tion 74 is provided with a metering slot 8| which trip arm 33 so that upon counterclockwise rotation of the lever Hby downward thrust of the rod 63, the arm 13 will lift the trip arm 30 and release the lever 34 to'close the' float operated valve member 21.

The lower,end portion of the meteringvalve stem 66 is of reduced diameter, as at 14, for a sliding fit in an annular flange 15 within a valve seat member 18- which is press-fitted in the outlet conduit 11 leading from the reservoir 28. .The conduit I1 has an internally screw-threaded fitting i8 projecting from the bottom wall of the casing 31 and into which the end of the fuel conduit 1 is secured as by screw-threaded engagement. Communicating with the conduit 11 and extending upward from the fitting 18 there is a vent passage"!!! for relieving the conduit 1 of any fuel, entrained air or gas. The lower end portion of the stem 86 has an internal longitudinal bore 80 which extends upward to a point above maximum liquid level in the reservoir 28 so as to vent the passageway or conduit Iof any fuel, entrained air or gas. The reduced "stem end poris tapered at its upper end for pilot flow, the slot cooperating with the flange 15 to meter flow from the reservoir 20 to the burner 61' Above the reduced portion 14, the stem has aconical portion 82 which is engageable with .the upper end of the valve seat member 16 to close off or stopthe flow of fuel from the reservoir 26 to the conduit 11. Loosely fitting on the stem 66 above the conical portion 82 there is a sleeve or tubular member 83 which is urged upward by a helical coil spring 84 seating at its lower end on the bottom wall of the casing 31 and surrounding the seat member 76. The upper end or face of the sleeve 83 is engageable with a pin or arm 85 extending radially outward from the stem 66 so that'the spring .84 acting upward through the sleeve 83 against the pin 85 acts to move the valve 14 toward open position, see Fig. 1. Positioned laterally of the stem 66 and at diametrically opposite points there are a low fire adjustment screw 86 and a high fire leaf type toggle spring 84 so positioned relative to the lever 53 that its component of force oppos-' ing rotation of lever 53 will decrease at such a rate that the force which will initiate movement of the lever 53 will cause movement of the lever 53 through its complete range of travel. Extending from the lever 53 adjacent and on the ,power.

element side of the bridge member 8| which limits upward movement of the lever 53 by the spring 64, there is a valve operating arm 85 apertured for passage -of a'metering valve stem-86 therethrough and having oppositedowntumed bearingportions for engaging the top face of a collar 61 slidable on the stem 66. This metering valve operating mechanism is more fully'described 'in- ,my Patent 2,342,633, grantedFebruary 29, 1944,

for Control means. v

Secured inan aperture in arm- 85, there is an internally threaded sleeve or ,nut 68 through which there is adjustably screwthreaded an operating rod 68 for-actuating the safety trip mechanism, a lock nut 18 being provided to hold the rod 68 in adjusted position. The rod or thrust member 63 extends downward into the casing 31 and terminates in overlying relation, see Fig. 4, to one end'portion of a release lever 'Il carried by and journaled on the valve closing lever 34 by a bear adjustment screw 81 which are adjustably screwthreaded into supporting bosses 88, 83 respectively extending upward from the bottom. wall of the casing 31. Slidable on the screw 88 there is an adjustable low fire stop member 38 in the form of a sleeve having a lateral flange 3| at its lower end, the member 30 being supported. on a stitf helical coil spring 32 which surrounds the screw 86 and seats on the boss 88. Cooperable with the member '38 there is an arm 33 which extends -radially and horizontally from the sleeve 83 and is notched or apertured at its end to slidably fit the member 96 to hold the sleeve 83 against-rotation and to engage the top face of the flangejSl to limit downward movement of the sleeve 83 and of the stem 68 when pin 85 is in engagement with'the sleeve top face, as in Fig. 1. Suppor d on the sleeve member 38 andastifl helical spring 34 surrounding the high -fire adjustment'screw 81 there is a cam track means 85, see Flg.',3-. The cam track member 36 has an apertured ear 3! received by the screw 86 and seating on: the

sleeve 38. overlying the ear 31 and the low fire 1' end portion 88 of the member 38 there-is a-resil'- ient track member 33 havingan apertured arm I88 which fits over the screw 88. The member 33 has an inverted U-shaped end sectionto. hold it laterally in registry with the end portion 88 and has a downward inclined side edge I8I leading from the portion 88 as a flexible track extension. Also meived by the screw 88 is the apertured end portion I82 of a cam seating member I88 having a horizontal step I84 cooperable with the valve stem pin 88 to seat and hold the conical valve portion 82 in engagement with the seat member 18. The other end of the cam seating member I88 is apertured, as at I88, to receive the screw 81 and to be held in engagement with the topface of the boss 88 by the overlying spring 84. The high fire end of the cam track 88 has an apertured ear I88 which receives the screw 81 and .seats on the top face of the stiff spring 84. Se-

' bears upwardly against the under face of the track member 88 or the step I84 of the member I88 or the resilient track edge I8 I. The top edge of the sleeve 88 has a recess or notch I88 positioned beneath the step I84 and has a downward inclined cam edge II8 leading from beneath the flexible track edge I8I so that upon rotation of the stem 88, the pin 88 'will move down along the track member 88 and from the track edge IM and into the recess I88 under the resilient downward force of the member I88, the arm 88 and flange 8| preventing further downward movement-of the sleeve 88.

Above the cam means 88, the stem 88 has an annular upward facing shoulder III on which is seated the lower end of a helical coil'compression spring II2 which surrounds and acts at its upper 1 end against the collar 81 to hold the collar against a downward facing annular shoulder 'I I8 on the stem 88. Preferably the'collar 81 is reciprocal on a stem extension II4 fitted into a stem end bore and pinned therein, as at II8, so that the parts can be assembled. The stem 88 extends upward through an aperture H8 in ahorizontal shelf or supporting plate member II1 preferably cast integral with the housing member 88 and thence through. a registering aperture H8 in the cover member 48. J ournaled in the aperture I I8 The low fire adjustment screw 88 is set to position the flange 8| such that, with the arm 88 in position, it will be riding on the top face of the sleeve member 88. It maybe noted that the aux iliary track member I8I provides a flexible resilient end portion for'the main track member 88, thereby to accommodate manufacturing tolerances in the spacing between the low cam end 88 and the top face of sleeve member 88. The high fire adjustment screw 81 is set to position the high end of the main track member 88 at the maximum permissible fuel flow to the burner 8. The thrust member 88 is adjusted relative to the force of spring II2 so that the lower end of the thrust-member 88 will actuate the release lever 1| upon predetermined temperature increase above the temperature at which the arm 88 will there is a tubular hand adjustment member or knob I I8 which extends upward through the cover aperture 8 and islongitudinally slotted upwardly, as at I28, at a plurality of points from its lower end. Each of the downward extending knob fingers is of reducedwidth at its lower end portion to'pass' through aligned arcuate slots in clamping washers I2I, I22 which engage the top and bottom faces respectively of the shelf 1. The finger shoulders engage the top face of the washer I2I so that the lower ends of the knob fingers turned or bent outward, as at I28, lock and hold the knob |I8 longitudinally fixed for rotation in the shelf aperture II8, see Fig. '7. The stem extension I I4 extends upward through the washers I2I, I22 and has, at its upper end, a disc- I24 with arcuate slots through which the knob fingers slidably fit so that rotation of the knob III acts through the disc I24 to rotate the stem 88, thereby to reciprocate the stem as the pin 88 is moved along the cam means. The disc I24 is carried by a pin I28 which fits in a longitudinal bore or socket in the upper endof the stem extension H4 and is held against rotation relativeto the extension II4 by a cross pin I28 which fits in a stem end slot I21. The operation of the apparatus is as follows:

v have been moved into engagement with the flange quick action, thereby permitting the spring 84 to move the valve stem 88 upward until the follower member 88 engages the main track member 88, as shown in Fig. 1. Any desiredfuel flow to the burner can be obtained within the minimum and maximum limits set by the low fire screw 88 and the high fire screw 81 respectively by merely rotating the stem 88 to regulate the lift of the follower member 88 before its engagement with the cam track means. When the temperature is reached at which the power element 48 is set to operate by the prior adjustment of screw 88, the lever 88 will be moved downward with a quick action, compressing the spring 84 and moving the arm into engagement with limit flange 8|.

This downward movement of the lever 88 will not compress the spring 2 since it exerts a greater resistance than the spring 84. If the temperature increase which resulted in downward movement of the lever 88 was caused by an obstruction to outflow oi the heated air through the grill 8 from passageway I8, as for instance by the positioning of a rug over the grill 8, then the temperature surrounding the bulb element 41 will increase and when the temperature has risen to the predetermined safe limit as determined by the adjustment of the thrust member 88, then the further expansion of power element 48 will have compressed the spring I sumciently so that release lever 1| will have moved the trip arm 88.

upwardly, thereby releasing the lever 84 for closing of the inlet valve 2| under the force of spring 88. Fuel fiowto the burner 8 will-now continue at a decreasing rate until the fuel in the cham-- ber 28 is. consumed. This small quantity of fuel which is burning at a decreasing rate will not passageway, ali'quia fuel bumar fol-"said ch might still be so hot that an explosion would occur. After the power' element 43 has tripped the safety mechanism 3| and has cooled to a position calling for heat, such as'shown in Fig. 3, then the trip mechanism can be manually reset to the position of Fig. 3 by lifting upward-on the lever extension 36 sufiiciently to position the latch platen above the pawl 32. If it is desired to shut down the burner -6, the hand grip member I I9 is rotated to move the follower member 85 ofl the end of the main track member 95 and into underlying relation to the step I04, which is possible.

by reason of the sleeve member recess I09 which permits the stem 66 to move downward beyond the limit set by flange 9|, the resilience of the track member I03 acting to hold the conical valve portion 82 tightly against its seat on the member It may be noted that if it is desired to provide a control device in which. the metering valve is modulated in accordance with the temperature of the power element 43, that this may be ac complished by changing the angle at which the spring 64 acts on the lever 53, so that the sum of the power element resisting component of force of the spring 64 and the force of the spring 58 does not decrease upon movement of the lever 53 by the power element 43, asis well known to those skilled in the art;

What is claimed and is desired to be secured by Letters Patent of the United States is:

1. A heating apparatus comprising a furnace having a combustion chamber and an air flow passageway, a'fluid fuel burner for said chamber, a metering valve operable to regulate the supply of fuel to said burner, thermostatic means mechanically acting on and for regulating said valve in accordance with air temperature in said passageway, means to stop closing movement of and determining the minimum low fire open position of said valve, 9. control valve operable toshut oil the supply of fuel to said burner, a springtrans mitting motion from said thermostatic meansto' said metering valve and providing forcontinued movement of said thermostatic means upon stopping of said metering valve by said determining means, releasable means under-tension operable to strike and move said control valve to.closed position, and means mechanically transmitting the continued movement of; said thermostatic means to said releasable-means to release said releasable means. 1 I 1 v v 2. A heating apparatus comprising afurnace having a combustion'chamber and an air flow passageway, a fluid fuel burner for said chamher, a rotatable and longitudinally reciprocal metering valve operable upon-reciprocation to regu late the-supply of fuel to said burner, thermostatic means to reciprocate said valve in accordance with *air temperature in said passageway, a lever mechanically interconnecting said thermostaticmeans and'said valve,'means to stop the closing movement 'of and determining the minimum low fire open position of said valve, a stop member on said valve and engageable with said stop means, a control valve operable to shut off the'sup'ply of fuel to said burner, a spring transmittingmovement of said lever to said metering valve and providing for continued movement of. said thermostatic means upon limitation-of said metering valve by said determining means, manual means to rotate said metering valve to move said stop member out of engaging relation to said stop means thereby to. permit movement of said metering valve toward closed position beyond the .limit of said determining means, and means operable by said thermostatic.

means and acting upon'said continued movement to close said control'valve Y 4. A heating. apparatus comprising a furnace having, a combustionvv chamber and an airflow passageway, a fluid fuel burner for said chamher, a metering valve operable to regulate the supply offuel to said burner, thermostatic means mechanically acting on and for regulating said valve inaccordance with air temperature in said passageway, means determining the .minimum open position of said valve, a control 'valve operable to shut off the supplyof fuelto said burner, a spring transmitting movement from said thermostatic means to said metering valve and providing for continued movement of said thermostatic means upon limitation of said metering valve by said determining means, releasable means operable to move said control valve to closed position, and a thrust member operable to transmit movement to said releasable means the temperature of said thermostatic means at which said thermostatic means will release said releasable means.

5. A control device for liquid fuel burners comprising a constant level liquid reservoir having an inlet and an outlet, a float operated valve con-.

trolling said inlet, a metering valve controlling said outlet, a lever operable toactuate said nic bet, a liquidfuel reservoir, a valve operable-to regulate the supply of fuel *from said reservoir to said burner, thermostatic means for regulating said valve-in accordance with air temperature in said passageway, mean determining the minimum open position of said valve, a control valve responsive. to liquid level in said reservoir. and

operable'to'shut off the supply of' fuel to said ued movement of said thermostatic means upon limitation ofsaid first-named valve by said de-' move said control valve to closed positionkjsaid burner, lost-motion means providing for contine I 't'ermining means, releasable means operable to' thermostatic mean acting upon said continued 3 movement to release said-releasable means, and means, operable to release said releasable means upon occurrence of excess liquid level in said reservoir.

3. A heating apparatus comprising a furnace having a combustion chamber and an air flow tering' valve,- temperature responsive means: di- 1 rectly acting on' -and throughvs'aid lever andurg- {in'g said .mj jl i ng' valve-to. a closed position at T a predetermined high temperature, safety trip mechanism. operable to close said-floatvalve upon occurrence of an undesired increase of liquid level,'normally inactive safety means including a thrust member operable by said lever to releasesaid trip mechanism, and means determining the increased temperature of said responsive means above said high temperature at which said thrust member will release said trip mechanism. v

' 6. A control device for liquid fuelburners com- "prising a constant-level liquid reservoirhaving an inlet and'an outlet, a that operated valve-controlling said inlet, a metering valve controlling said outlet, a lever operable to actuate and having a lost-motion connection with said metering valve, safety trip mechanism operable to., ,close said float valve upon occurrence of an undesired having a combustion chamber and an air flow passageway, a fluid fuel burner for said chamber, a rotatable and longitudinally reciprocable valve operable to regulate the supply of fuel to said burner, thermostatic means for longitudinally reciprocating said valve to regulate flow to said burner in accordance with air temperature in said release lever upon temperature increase above the temperature at which said metering valve is limited by said limiting means.

7. A control device for liquid fuel burners com prising a casing having a constant level liquid fuel chamber with an inlet and an outlet, a float valve controlling said inlet, a float operated lever pivotally connected to and for actuating said float valve to maintain a constant liquid level and having .a lost-motion connection at its fulcrum, a safety trip lever engageable with and urged toward said valve, a trip arm releasably holding said trip lever against movement and operable by said float operated lever upon increase of liquid level above the constant level, a release lever carried by said trip lever and operable to move said trip arm, a longitudinally slidable and rotatable metering valve having a stem and controlling said outlet, a low-fire fuel flow adjusting screw and a high-fire fuel flow adjusting screw positioned diametrically and longitudinally of said metering stem, a sleeve on said low flre screw and having a minimum limit flange, a coil spring on said low-fire screw and supporting said sleeve, a coil spring on said highflre screw, a main cam track member apertured to receive said screws and seating on said sleeve and said high-fire spring, a resilient valve shut of! cam track member apertured to receive said screws and having a shut off step at the low end of said main track member, an auxiliary track member carried by said low-fire screw and'extending along and beneath the low end of said main track member and leading to said step, a cam follower member projecting from said stem and engageable with underfaces of said main track, said auxiliary track and said shut off track members, a sleeve member on said stem and having an arm in guided sliding engagement with said sleeve and engageable with said limit flange, a coil spring surrounding said stem and urging said sleeve member against said follower member thereby to urge said valve toward open position, said sleeve member having a top edge recess positioned beneath said step to receive said follower member for movement of said valve to closed position, a collar slidable onsaid stem, means resisting downward sliding movement of said collar, an automatically operable lever engageable with said collar to move said meterin valve't'oward closed position and said sleeve memher arm against said limit flange, a thrust member longitudinally adjustably, supported by said automatic lever and operable to move said release lever, said automatic lever being operable to overcome said collar resisting means upon engagement of said arm and said limit flange and to move said thrust member into moving engagement with said release lever, and manually operable means extending out of said casing for rotating and for longitudinally reciprocating said stem.

. 8. A heating apparatus comprising a furnace said' passageway, a stop member engageable by said valve upon longitudinal reciprocation of said valve by said thermostatic means to determine the minimum open position of said valve, a control valve operable to shut off the supply of fuel to said burner, lost-motion means providing for continued movement of said thermostatic means upon limitation of said first-named valve by said determining means, and means to rotate said valve out of cooperable relation to said stop member so that said first-named valve can have movement toward closed position beyond the limit of said stop member, said thermostatic means upon said continued movement cooperating with said control valve.

91 A control device for liquid fuel burners comprising a constant level liquid reservoir having an inlet and an outlet, a float operated valve controlling said inlet, a metering valve controlling said'outlet, a lever operable to actuate said metering valve, safety trip mechanism operable to close said float valve upon occurrence of an undesired increase of liquid level insaid reservoir, a thrust member operable by said lever to release said tripmechanism, thermostatic means cooperable with said lever and operable at a predetermined temperature to move said metering valve to a low flre position, and means determining release of said trip mechanism by operation of said thrust member at a temperature of said thermostatic means above said predetermined temperature.

10. A control device for liquid fuel burners comprising a constant level liquid reservoir having an inlet and an outlet, 9. float operated valve controlling said inlet, a metering valve controlling said outlet, a lever operable to actuate and having a lost-motion connection with said metering valve, safety trip mechanism operable to close comprising a liquid reservoir having an inlet and an outlet, a valve controlling said inlet.

safety means operable to move said valve to.

close said inlet, a lever controlling operation of said safety means, a' metering valve for said outlet, means to limit closing movement of said metering valve to a minimum open position, tem- -perature responsive means having a driving connection with said valve and acting through said connection upon temperature increase to move said metering valve to said minimum open position, means in said driving connection and-providing for overtravel of said thermostatic means upon temperature increase subsequent to movement of said metering valve to said position, and means operable by said thermostatic means to move said lever to effect operation .ofsaid safety means upon said overtravel.

WALTER s, Lennon. 

